This invention relates generally to protective devices for a fire hydrant, and more particularly to a tamper-proof cover for the operating nut of a fire hydrant.
The unauthorized operation of fire hydrants is a common urban problem having possibly severe consequences, such as the waste of large quantities of water and the resulting substantial drop in an area's water pressure. Moreover, such tampering oftentimes result in damage to or loss of the operating nut of the fire hydrant.
There have been a number of attempts to protect the operating nut of the hydrant from access by unauthorized persons. For example, U.S. Pat. No. 2,118,233 granted May 24, 1938 discloses a hydrant guard having a cap held above the operating nut of the hydrant by means of downwardly depending legs. The legs are secured at their lower ends to a flange at the base of the bonnet. The top of the cap has a central opening therein for access to the operating nut.
U.S. Pat. No. 3,453,655 dated Dec. 19, 1966 discloses a dome-shaped guard integrally formed with the bonnet of a hydrant. The guard has a top opening in it through which a wrench with a socket member may be inserted for turning the nut.
U.S. Pat. No. 3,709,249 issued Jan. 9, 1973 shows an anti-tamper device for a fire hydrant comprising a washer which encircles the operating nut of the hydrant and rests on the bonnet of the hydrant, a cylindric collar around the operating nut having a circular shoulder at its upper end, the bottom of the collar being engageable at its lower end with the washer, and an externally threaded ring which encircles the collar below the shoulder of the collar. The device further includes an outer member having a closed top and an internally threaded skirt which is threadably engageable with the ring for concealing the operating nut from view. A special wrench is used to turn the operating nut.
Reference may also be made to U.S. Pat. Nos. 3,914,966 and 4,398,556 which disclose protective devices generally in the field of this invention.